Here's what I see: This is a very specific server. We tried connecting to your servers from various IP addresses, but all connection attempts were rejected with error messages similar to the one you sent me. I get the impression that you need to contact them to ask them to accept connections from the IP addresses to which emails are to be sent. I suggest contacting your point of contact at this domain through other means, whether by phone, WhatsApp, or another email address they receive—perhaps one from Germany—and asking your provider to adjust the settings so that emails sent from the IP address 148.251.119.178 are accepted. You can point out that our server is legitimate, does not send spam, is not on any blacklists, and uses all protocols for validating email delivery, including SPF, DKIM, and DMARC.

This email address cannot send me emails because they keep getting bounced back to the sender. All other email addresses work, just this one doesn't.